In the preparation of dyestuffs, m-amino-.alpha.-methylbenzyl alcohol is a useful intermediate which can be readily introduced into chromophoric molecules to produce useful dyestuffs. For example, m-amino-.alpha.-methylbenzyl alcohol may be condensed with haloanthraquinones to yield arylaminoanthraquinones which, when devoid of water solubilizing groups such as sulfo and carboxy, find utility in the field of polyester dyestuffs. In spite of the fact that such end product anthraquinones would be good dyestuff, their use has been somewhat restricted by the difficulty of obtaining the necessary starting material, m-amino-.alpha.-methylbenzyl alcohol, in a facile, inexpensive manner. Various researchers have reported on new ways for the synthesis of m-amino-.alpha.-methylbenzyl alcohol, but for the reasons set forth hereinbelow there are numerous drawbacks to such methods.
There are numerous reports in the literature of the hydrogenation of m-nitroacetophenone to m-aminoacetophenone under a relatively low hydrogen pressure such as 2- 5 atoms, in various solvents using the common hydrogenation catalysts such as nickel, palladium, and platinum. Reports of such research are found in Chemical Abstracts, 46, 10180i; 47, 5380e; 55, 25795e; and British Pat. No. 1,104,168. Such methods suffer from drawbacks, however, in that the second stage hydrogenation of the intermediate m-aminoacetophenone to the desired m-amino-.alpha.-methylbenzyl alcohol is reported only under extreme conditions such as 2000 psi to 4700 psi at 120.degree. C. to 155.degree. C., as reported in British Pat. No. 758,993 and U.S. Pat. No. 2,680,136. Thus, the prior art method requiring a two-step hydrogenation and the use of very extreme conditions in the second stage represents a distinct drawback to the worker of ordinary skill in the art faced with the problem of producing economical intermediate products for the synthesis of dyestuffs.
In British Pat. No. 758,993 there is described a proposal for the one-step catalytic preparation of m-amino-.alpha.-methylbenzyl alcohol from m-nitroacetophenone, but a pressure of 2000 psi at 120.degree. C. is required, Raney nickel being used in a dioxane solvent. A two stage process is discussed in U.S. Pat. No. 2,680,136 where m-nitroacetophenone is first catalytically reduced to m-amino-acetophenone under mild conditions which utilizes Raney nickel. However, the second stage requires the use of high pressure on the order of 4700 psi to 4800 psi with a copper chromite catalyst at a temperature of in excess of 150.degree. C.
From the foregoing, it is seen that most of the prior art processes discussed herein require a two stage treatment. Furthermore, the prior art processes teach the conversion of the starting or intermediate material to m-amino-.alpha.-methylbenzyl alcohol only under extreme conditions of pressure.
It is also known that m-amino-.alpha.-methylbenzyl alcohol, being a benzyl alcohol, is subject to possible hydrogenolysis in the presence of a certain hydrogenolysis catalysts to m-ethyl-aniline. The facile hydrogenolysis of benzyl alcohols (cleavage of the benzyl-oxygen bond) is well recognized and the reaction description appears in standard texts on catalytic hydrogenation (e.g. Catalytic Hydrogenation, R. L. Augustine, Marcel Dekker, Inc., N.Y. 1965, chapter 6: Catalytic Hydrogenation Over Platinum Metals, P. N. Rylander, Academic Press, N.Y. 1967, chapter 15 and 25). According to these texts, benzylic oxygen is readily cleaved with a palladium catalyst. Furthermore, mineral acids greatly facilitate such cleavage.